Travel by air has always been a contact sport. But today it got a bit rougher at the country's busiest airport. Thousands of passengers in Atlanta sat in darkness while multiple airlines shifted their schedules and diverted their international flights to other cities. The cost?

No cause was given for the blackout that occurred just before noon on Sunday. But the power outage knocked out the equipment that allows airlines to check in and to seat passengers on their planes. Southwest Airlines said it had to cancel all flights to the Hartsfield-Jackson International Airport for the balance of the day. Ditto for United. Delta Airlines, which is based in Atlanta, told its passengers to check its website for any updates.

"The FAA tower can operate normally, however, departures are delayed because airport equipment in the terminals is not working," the Federal Aviation Administration said in a statement. At the time of the power outage, it ordered all flights into Atlanta to stay where they were.

The airport said at 7 pm EST that power would be fully restored by midnight. But Georgia Power, whose parent is Southern Co., had not pinpointed the exact cause of the blackout when this story was published. Alternate equipment was turned on, however, although many parts of the airport were said to have been disabled. That includes the numerous businesses that dot every terminal at the airport.

Perhaps the most well-known power outage played out on international television in 2013 during the Superbowl. At the start of the second half, the lights went out and the game stopped for 34 minutes.

What are the solutions to these types of incidents? Accenture reported in 2013 that just a quarter of utility customers have confidence in utilities, meaning they would seek alternative ways to get their electricity if such options became cost effective and commercially available. That would include generating power onsite and delivering that electricity via microgrids -- a phenomenon, ironically, that could mean less investment in the centralized grid.

Some forecasts say that the U.S. economy loses more than $150 billion annually to power outages, which Accenture said erodes customer satisfaction and shareholder value.

“In the evolving energy marketplace, many utilities are at an inflection point at which they should redefine their role in consumers’ lives and refocus on building a base of trust,” says Greg Guthridge, managing director of Accenture Energy Consumer Services. “The first step is making interactions simple, in particular getting the basics right the first time. Each touch point with the consumer is critical – whether it involves mobile or digital options for straightforward transactions, or higher-touch interactions to resolve issues.”

Just as Delta Airlines has digital applications to keep connected customers in the know, utilities also need to make their solutions more accessible.

For utilities, they need to able to reduce peak demand by sharing information with customers. That, too, boost returns; data is then used to change consumption habits, saving energy and money.

As such, electrons can be redirected if there is congestion, which can make room for green energy. Smart grids, as they are called, can do real time monitoring and isolate problems, preventing them from spreading. Ultimately, the grid should become resilient and avoid major outages that would disrupt any individual businesses’ services or the economy as a whole. Production is thus sustained.

The Galvin Electricity Initiative has said that for every dollar spent on modernizing grid operations, $4 or $5 is returned -- a figure arrived at by calculating not just electricity savings but also by added productivity and job growth.

Consider those numbers when trying to calculate the opportunity cost of not just today's missed flights and business meetings but also the cost to those restaurants, bookstores and other vendors that had to shut down inside Atlanta's airport, even temporarily.

Follow Up: Monday December 18

– About 1,000 flights in all were canceled on Sunday before the power was turned back on at midnight.

— Georgia Power said that electrical fire disabled substations at the airport, knocking out not just the main power source but also the redundant one that turns on when there is an emergency. "Georgia Power has many redundant systems in place to ensure reliability for the Airport and its millions of travelers - power outages affecting the Airport are very rare," a statement read.